1. Field of the Invention
The present invention relates to an endoscope imaging apparatus including an imaging unit having an imaging optical unit and an imaging element unit.
2. Description of Related Art
Conventionally, there are widely employed endoscope imaging apparatuses connected to an optical observation tube, and the like inserted into a body to display an endoscope image on a screen such as a monitor, and the like by converting an optical image captured by the optical observation tube into electric signals.
For example, Japanese Unexamined Patent Application Publication No. 8-248465, Japanese Examined Utility Model Publication No. 61-19584, U.S. Pat. No. 4,972,268, and the like disclose ideas as to the adjustment of the position where an imaging element is disposed with respect to an imaging optical system and as to the attachment structure of the imaging element.
Recently, endoscope imaging apparatuses, and the like having a possibility that they are indirectly in contact with organs, and the like when they are in use must be sterilized and disinfected after it has been used. Autoclave sterilization is available as the sterilization means. The autoclave sterilization is high temperature high pressure steam sterilization, operates at low running cost, and has high reliability.
In the autoclave sterilization, however, since endoscope imaging apparatuses are exposed to high temperature and high pressure steam, the entry of the steam into the inside of the imaging apparatuses must be prevented. To cope with this problem, the endoscope imaging apparatus is required to have water tightness, which prevents the entry of a liquid in the inside of the apparatus even if it is dipped in the liquid, and air tightness that is more higher than that in an ordinary atmospheric pressure.
Accordingly, metal, ceramics, glass, and a crystalline material that prevent the permeation of high temperature and high pressure, and a resin material, and the like that have very small stream permeability are selectively used as a material for constituting the endoscope imaging apparatus. In contrast, an air tight joint, for example, soldering, brazing, and the like is used as a joint means for joining materials with each other, in which metal, ceramics, glass, a crystalline material, and the like are used as a main component of the joint.
For example, Japanese Unexamined Patent Application Publication No. 2000-075218 discloses an endoscope apparatus in which an outer sheath is composed of metal as far as possible and a joint is airtightly joined by soldering. In this endoscope apparatus, a space in an optical axial direction, in which an optical system moves, is covered making use of a metal bellows.
However, in the many ideas described above as to the position adjustment and the attachment structure of the imaging element, adjustment in optical axis direction, adjustment of decentering, adjustment of tilt, and the like are carried out independently. Since the imaging element is arranged to cope with all the adjustments, when all the adjustments are combined, the number of parts of the endoscope imaging apparatus is greatly increased, from which a problem arises in that cost is increased, the size of the apparatus is increased, and the adjustment of the apparatus is troublesome.
It is contemplated to arrange all the components from an imaging optical system to an imaging element in an airtight sealed state for preventing the entry of steam from the outside. In this arrangement, however, it is difficult to perform the aforementioned positional adjustment of the imaging optical system and the imaging element and to provide the aforementioned attachment structure with them. Further, the provision of the above structure results in such disadvantages that the size of the apparatus is further more increased and that various adjustments must be performed before the components are airtightly sealed as well as an allowable level to an optical performance is reduced by performing the various adjustments before they are airtightly sealed.
Further, recently, a technology for performing diagnosis using special light such as infrared light, fluorescent light, and the like is becoming widespread. For example, Japanese Unexamined Patent Application Publication No. 7-155291 discloses a fluorescent light observation endoscope apparatus having a rotary filter disposed therein, rotated by a motor, and including a filter formed of an optical lens for passing white light therethrough and a similar filter for passing fluorescent light of a particular band therethrough. This endoscope imaging apparatus can also perform observation with fluorescent light by disposing a filter corresponding to the fluorescent light by rotating the rotary filter according to a type of illumination light emitted from a light source.
In addition to the above apparatuses, there is also an endoscope imaging apparatus arranged separately from an optical adaptor acting as a lens unit so that it can perform observation with special light through a dedicated optical adaptor to which a filter for observation with special light is attached.
To permit the aforementioned fluorescent light observation endoscope apparatus to be subjected to autoclave sterilization, however, it is necessary to dispose the rotary filter and the motor in an airtight unit. Then, there is a possibility not only that a structure in which they are disposed is made complex and expensive but also that the apparatus is increased in size and weight and imposes a burden on a user and that the operability of the apparatus is lowered.
Further, when the endoscope imaging apparatus is arranged separately from the optical adaptor, they must be autoclave-sterilized individually. Accordingly, the endoscope imaging apparatus must be connected to the optical adaptor in a state in which the joint thereof is sufficiently dried after the apparatus is autoclave-sterilized. This is because that when the joint is dried insufficiently, there is a possibility that a cover glass in the vicinity of the joint tarnishes while the apparatus is being used. That is, in this separate arrangement, there is a possibility that the advantage of the autoclave sterilization that the apparatus can be used at once after it is sterilized can not be exhibited.
Further, there are conventionally proposed endoscopes the operability of which is improved by removing angle down by disposing a small motor at an extreme end. For example, Japanese Unexamined Patent Application Publication No. 10-127568 proposes a zoom type endoscope capable of performing a stable zoom drive even if a small motor having a small output is used. Further, Japanese Unexamined Patent Application Publication No. 2001-008886 proposes an endoscope having an air vent disposed at a part of a moving lens frame so that a moving lens can move smoothly.
However, in the zoom type endoscope of Japanese Unexamined Patent Application Publication No. 10-127568, since an optical member moving mechanism, which acts as a target lens moving frame and lens frame support member, is directly mounted on a rotary power source, it is necessary to assemble them with a pinpoint accuracy, and thus a structure is increased in size and made complex.
In contrast, in the endoscope disclosed in Japanese Unexamined Patent Application Publication No. 2001-008886, since an optical member moving mechanism is disposed spaced apart from a power source, a drive force is transmitted by a push/pull operation in place of the transmission thereof by rotation.
A first object of the present invention is to provide an endoscope imaging apparatus in which an imaging optical system and an imaging element are airtightly sealed and in which the positions of the imaging optical system and the imaging element can be easily adjusted from the outside of these components having been airtightly sealed.
A second object of the present invention is to provide an endoscope imaging apparatus which can airtightly seal an imaging optical system and an imaging element, improve an optical capability, and reduce the size thereof at a less expensive cost.
A third object of the present invention is to provide an endoscope imaging apparatus which can easily change filters, is excellent in operability, has a simple structure, is less expensive, and can be subjected to autoclave sterilization.
A fourth object of the present invention is to provide an endoscope imaging apparatus that transmits rotation from a rotary power source for moving optical members such as a lens, and the like, and makes complex axial alignment of pinpoint accuracy unnecessary.